The invention concerns an electric switchgear with a pole filled with insulating gas, a monitoring device for the insulating gas in the pole of the switchgear, and a test connection for a testing device to test the monitoring device.
A three-pole high-voltage switchgear usually has three of the switchgear poles mounted on a frame. These poles can be power circuit breakers, isolating switches, grounding switches, or the like. At the foot of each pole of the switchgear, there is a case containing the drive mechanism for the respective pole of the switchgear. The cases of the three poles of the switchgear are connected to each other by another drive support and are connected to a switching drive. In the switching process, the poles of the switchgear are switched from the first switching state to a second switching state or back by the switching drive via the drive support.
Because of the high voltage being switched, the poles of the switchgear and the case that goes with them are filled with an insulating gas. For this insulating gas to be able to perform its insulating function and above all its function of quenching a potential arc, the insulating gas must be kept under a predetermined minimum pressure. This minimum pressure must be maintained for the switchgear to be able to work safely.
It is known how to monitor the pressure acting on the insulating gas. For this purpose, the cases of the three poles of the switchgear are connected to a monitoring device through a tube connection that has a pressure sensor. When the switchgear is operating, the pressure on the insulating gas is then measured at all times by the pressure sensor and monitored by the monitoring device.
But for the pressure of the insulating gas to be monitored, the pressure sensor in the monitoring device must be working and must display the correct pressure.
It is known how to check the monitoring device from time to time. This can be done by detaching the tube connection from the case, and hence from the switchgear poles. For the switchgear poles to work in this detached state, return valves must be provided to prevent the insulating gas from escaping from the switchgear poles. When the switchgear poles are separated, the monitoring device, and especially the pressure sensor in it, can be checked to see that they are working and that the measurements are precise. The free ends of the tube connection are thus provided with return valves or sealed with vent plugs. Then a testing device can be connected to the monitoring device. The pressure sensor of the monitoring device can then be submitted to a test pressure by the testing device. The pressures displayed by the testing device and the monitoring device can be compared. After the test, the testing device must be removed and the tube connection reconnected to the cases and the switchgear poles.
Obviously, the process described above for checking the monitoring device is very time-consuming. Some of the measures required, namely detaching and reconnecting the tube connection to the switchgear poles, must be done in direct proximity to these poles. This is only possible if special measures are taken to protect the test personnel, since the switchgear is most often operating and powered up during the tests, so the test personnel must be prevented from getting too close to live parts.
The problem of the invention is to create an electric switchgear in which it is possible to check the monitoring device for the insulating gas in a less time-consuming way.
The invention solves this problem with the electric switchgear in laim 1.